UNCTAD released the report as it hosted a two-day meeting on measuring e-commerce and the digital economy.
According to the report, online retail sales grew markedly in several countries, with South Korea reporting the highest share at 25.9% in 2020, up from 20.8% the year before.
Meanwhile, global e-commerce sales jumped to $26.7 trillion in 2019, up 4% from 2018, according to the latest available estimates.
This includes business-to-business (B2B) and business-to-consumer (B2C) sales, and is equivalent to 30% of global gross domestic product (GDP) that year.
"These statistics show the growing importance of online activities. They also point to the need for countries, especially developing ones, to have such information as they rebuild their economies in the wake of the covid-19 pandemic," said Shamika Sirimanne, UNCTAD’s director of technology and logistics, in a press release on Monday.
The report estimates the value of global B2B e-commerce in 2019 at $21.8 trillion, representing 82% of all e-commerce, including both sales over online market platforms and electronic data interchange (EDI) transactions.
The United States continued to dominate the overall e-commerce market, ahead of Japan and China.
B2C e-commerce sales were estimated at $4.9 trillion in 2019, up 11% over 2018.
The top three countries by B2C e-commerce sales remained China, the United States and the United Kingdom.
Cross-border B2C e-commerce amounted to some $440 billion in 2019, an increase of 9% over 2018.
The UNCTAD report also notes that the share of online shoppers making cross-border purchases rose from 20% in 2017 to 25% in 2019.